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This structure forms when an extra X chromosome is methylated and largely inactivated. It is most commonly found in females

Barr body

____________________act as intermediaries between ______________________________ and specific _____ sequences to modify chromatin structure and activate transcription

Transcriptional activators, chromatin-remodeling complexes, DNA

A eukaryotic DNA sequence that affects transcription at distant promoters is called a(n) ________________.

enhancer

An insulator is also known as a __________________

boundary element

mRNAs are degraded by enzymes called ____________.

ribonucleases

Apurinic (and apyrimidinic) sites (AP sites) involve a spontaneous loss of ______________ in an intact double-helix DNA molecule

purine

Transposable elements are also known as:
Mobile genetic elements
Transformers
Jumping repeats
Jumping genes
Moving genes

>Mobile genetic elements
Transformers
Jumping repeats
>Jumping genes
Moving genes

Frameshift mutations are caused by the _________ or _________ of one or more nucleotides in DNA.

removal, insertion

Indicate the level of activity of the lac operon under the medium conditions listed below:

a) No lactose present, no glucose present
b) Lactose present, no glucose present
c) No lactose present, glucose present
d) Lactose present, glucose present

Enter "high" or "off", separated by a comma, in the order of the a, b, c, d scenarios into the answer box

off, high, off, off

What symbols are used to describe constitutive mutations in the lac operon?

I-, O^C

A promoter that affects only genes that are on the same piece of DNA is ____________-acting

cis

One type of mutation involves the replacement of a purine with a purine. What general term is associated with this mutational phenomena?

transition

It is estimated that transposable elements compose approximately what percent of the human genome?

50

Which of the following is NOT true regarding the differences in mRNA between prokaryotic cells and eukaryotic cells?
A) In eukaryotic cells, mRNA is spliced before translation, while in prokaryotic cells there is no mRNA splicing.
B) In eukaryotic cells, the 5' end of mRNA is modified with a cap, while in prokaryotic cells there is no cap.
C) In eukaryotic cells, the 3' end of mRNA is modified with a tail, while in porkaryotic cells there is no tail.
D) In eukaryotic cells, the transcription to mRNA and the translation from mRNA are coupled, while in prokaryotic cells transcription and translation are not coupled.

D) In eukaryotic cells, the transcription to mRNA and the translation from mRNA are coupled, while in prokaryotic cells transcription and translation are not coupled.

Which of the following terms best characterizes catabolite repression associated with the lactose operon in E. coli?
a) negative control
b) constitutive
c) positive control
d) inducible system
e) repressible system

c) positive control

Riboswitches were first discovered in 2002 and have been found in...
a) bacteria
b) In all of the listed organisms
c) plants
d) fungi
e) archaea
f) In none of the listed organisms

b) In all of the listed organisms

A _________________, which binds to a core promoter, consists of general transcription factors and RNA polymerase.

basal transcription apparatus

The ____________________ stabilizes the 5' cap, which must be removed before the mRNA molecule can be degraded from the 5' end

poly (A) tail

_______________ is also known as RNA silencing and posttranscriptional gene silencing

RNA interference

This term describes genetic elements that affect other elements only when they are located adjacent to them. For example, the operator has this effect on its structural genes

cis-acting

Proteins that affect chromatin structure without altering histone chemical structure are called _______________.

chromatin-remodeling complexes

A catabolite-activating protein (CAP) exerts _____________control over the lac operon.

positive

The process by which excessive numbers of a sex chromosome are corrected, often by methylating the X chromosome to form a Barr body.

dosage compensation

Regions of chromosomes that are inactivated through methylation are termed this.

silent chromatin

What is the common influence of ultraviolet light on DNA?

dimer formation

One type of mutation involves the replacement of a pyrimidine with a purine. What general term is associated with this mutational phenomena?

transversion

Choose the type of control illustrated by GAL4 in the control of genes for yeast galactose-metabolizing enzymes.
negative inducible
negative repressible
positive repressible
positive inducible

negative inducible
negative repressible
positive repressible
>positive inducible

Mutations which arise in nature, from no particular artificial agent are called
natural mutations
cosmic mutations
induced mutations
chromosomal aberrations
spontaneous mutations

natural mutations
cosmic mutations
induced mutations
chromosomal aberrations
>spontaneous mutations

Where would the lac repressor be bound in a (nonmutant) E. coli cell that is growing in low glucose and high lactose?
P
P and O
The repressor would not be bound.
I, P, O
O

The repressor would not be bound

Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from
Huntington disease
xeroderma pigmentosum
muscular dystrophy
phenylketonuria
SCID

Huntington disease
>xeroderma pigmentosum
muscular dystrophy
phenylketonuria
SCID

LINES differ from retrotransposons in that LINES:
do not encode reverse transcriptase.
do not contain LTRs.
do not transpose in a replicative manner.
do not encode transposase.
do not contain the transposase gene.

do not encode reverse transcriptase.
>do not contain LTRs.
do not transpose in a replicative manner.
do not encode transposase.
do not contain the transposase gene.

After translation, eukaryotic proteins can be modified by
acetylation.
the addition of phosphate groups.
the removal of amino acids.
the addition of methyl groups.
all of the above.

acetylation.
the addition of phosphate groups.
the removal of amino acids.
the addition of methyl groups.
>all of the above.

Which of the following is TRUE for both prokaryotic and eukaryotic gene expression?
A) RNA polymerase binds to the promoter region to begin transcription.
B) After transcription, a 3' poly-A tail and a 5' cap are added to mRNA.
C) mRNA is synthesized in the 3' → 5' direction.
D) The mRNA is the exact complement of the gene from which it was copied.

>>>-RNA polymerase binds to the promoter region to begin transcription.
-After transcription, a 3' poly-A tail and a 5' cap are added to mRNA.
-mRNA is synthesized in the 3' → 5' direction.
-The mRNA is the exact complement of the gene from which it was copied.

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation refers to
addition of methyl groups to the cytosine of CG doublets
changes in DNA-DNA hydrogen binding
altering RNA polymerase activity by methylation
altering translational activity especially of highly methylated tRNAs
alteration of DNA polymerase activity by addition of methyl groups to glycine residues

>addition of methyl groups to the cytosine of CG doublets
changes in DNA-DNA hydrogen binding
altering RNA polymerase activity by methylation
altering translational activity especially of highly methylated tRNAs
alteration of DNA polymerase activity by addition of methyl groups to glycine residues

E. coli lac operon control by lac I
positive inducible
negative inducible
positive repressible
negative repressible

positive inducible
>negative inducible
positive repressible
negative repressible

The following may be caused by mobile genetic elements except ________________
activate a gene in which they reside
cause chromosome breaks
disrupt a gene
undergo mutation
all of the above

activate a gene in which they reside
cause chromosome breaks
disrupt a gene
>undergo mutation
all of the above

Regulatory proteins that bind DNA have common motifs that interact with sequences of DNA.
How do amino acids in DNA-binding proteins interact with DNA?
By forming covalent bonds with DNA bases
By forming hydrogen bonds with DNA bases
By forming covalent bonds with DNA sugars
None of the above.
a) and c)

By forming covalent bonds with DNA bases
>By forming hydrogen bonds with DNA bases
By forming covalent bonds with DNA sugars
None of the above.
a) and c)

Insulators can block the effects of enhancers only when
they lie within the structural genes.
they lie adjacent to a promoter.
they lie upstream of a promoter.
they lie within a consensus sequence.
they lie between an enhancer and a promoter.

they lie within the structural genes.
they lie adjacent to a promoter.
they lie upstream of a promoter.
they lie within a consensus sequence.
>they lie between an enhancer and a promoter.

Which of the below is not true about the location of enhancers?
They can be found in introns.
The position of the enhancer has no effect on gene regulation.
They can be found upstream of the transcription initiation site.
They can be found downstream of the promoter.
They can be found 3' of the polyadenylation site.

The position of the enhancer has no effect on gene regulation

Name two mutagens which would be classified as base analogues.
a) 5-bromouracil and 2-aminopurine
b) ultraviolet light and cosmic radiation
c) acridine orange and proflavin
d) hydroxyurea and peroxidase
e) ethylmethane sulfonate and ethylmethylketone peroxide

>a) 5-bromouracil and 2-aminopurine
b) ultraviolet light and cosmic radiation
c) acridine orange and proflavin
d) hydroxyurea and peroxidase
e) ethylmethane sulfonate and ethylmethylketone peroxide

Which of the following clusters of terms applies when addressing enhancers as elements associated with eukaryotic genetic regulation?
cis-acting, vairable position, fixed orientation
cis-acting, variable orientation, variable position
trans- and cis-acting, variable position
cis-acting, fixed position, fixed orientation
trans-acting, fixed position, fixed orientation

cis-acting, variable orientation, variable position

siRNAs and miRNAs are produced by
the cleavage of RISCs by endonucleases.
the cleavage of functional mRNA within the cytoplasm.
the cutting and processing of double-stranded RNA by Slicer enzymes.
the cleavage of pre-mRNA in the nucleus.
the cutting and processing of double-stranded RNA by Dicer enzymes.

the cutting and processing of double-stranded RNA by Dicer enzymes.

A mutant E. coli strain, grown under conditions that normally induce the lac operon, produces high amounts of ß-galactosidase. What is a possible genotype of the cells?
lacI+ lacP+ lacOc lacZ+ lacY+ lacA+
lacI+ lacP- lacO+ lacZ+ lacY+ lacA+
lacI- lacP+ lacO+ lacZ- lacY+ lacA+
lacI+ lacP+ lacO+ lacZ- lacY+ lacA+

lacI+ lacP+ lacOc lacZ+ lacY+ lacA+

(I = lac repressor gene; Z, Y, A = lac operon structural genes; P = lac promoter; O = lac operator)

Which parts of the DNA region shown in the diagram encode proteins?
I, P, O, Z, Y, A
P, O, Z, Y, A
I, Z, Y, A
P

I, Z, Y, A

The lac repressor protein controls expression of the lac operon via ________________
binding to the lac structural genes to repress expression
binding of the lac Z and lac Y genes only
binding to the lac promoter site to repress expression
binding to the lac operator site to repress expression
all of the above

binding to the lac operator site to repress expression

It is possible for a repressor to negatively regulate the expression of an operon because
the repressor binding site overlaps the promoter site of the operon allowing it to physically block the binding of RNA polymerase.
the repressor induces the expression of inducer.
the repressor binding site on the DNA overlaps with the translation start site.
one of the genes expressed in the operon negatively regulates the repressor.

the repressor binding site overlaps the promoter site of the operon allowing it to physically block the binding of RNA polymerase.

When referring to attenuation in regulation of the tryptophan operon it would be safe to say that when there are high levels of tryptophan available to the organism...
tryptophan is inactivating the repressor protein.
ribosomes are stalling during translation of the attenuator region.
the tryptophan operon is being transcribed at relatively high levels.
translational termination is likely.
transcriptional termination is likely.

transcriptional termination is likely.

The region of a protein that is capable of holding on to a particular nucleotide sequence in order to affect proper gene regulation.

DNA binding domain

Transcriptional repression by methylation of DNA is most common in sequences called____________ islands.

CpG

The ____________________ consists of modifications to histone proteins that affect the expression of DNA sequences.

histone code

A condition in which a gene or group of genes is expressed all the time

Constitutive

Since the binding of the _________ to the _________ prevents it from binding to _________ by causing a conformational change in its structure, it is called an _________ protein.

Inducer, repressor, DNA, allosteric

When regions around genes become sensitive to the enzyme ______________this is an indication that those regions are becoming ______________ active.

DNase I, transcriptionally

The process of error correction of mismatched bases carried out by DNA polymerases is called

proofreading

This is the region of a gene where RNA polymerase binds to initiate transcription

promoter

Parts of chromosomes that are not methylated for inactivation, but rather are less dense-staining and are likely active in transcription in the cell.

euchromatin

A constitutive gene is _______ regulated and is expressed ____________.

not, continually

The molecular nature of transposable elements was first understood in E. coli due to the simplicity of the E. coli genome. Which of the following types of DNA contribute significantly to the genome complexity of other organisms?
LTR retrotransposons
LINES
SINES
Genes
IS elements

>LTR retrotransposons
>LINES
>SINES
Genes
IS elements

These are factors that need not be adjacent to the genes they control. An example would be the lac operon's repressor protein.

Trans-acting

List five levels at which gene control can take place in eukaryotes.

1. Alter structure- modify DNA or packaging
2. Transcription
3. mRNA processing-5' cap, 3'cleaved and polyadenylated, introns removed
4. RNA stability
5. Translation- large number of enzymes, protein factors, and RNA molecules

A _________ mutation changes a codon that specifies an amino acid into one that terminates translation.
neutral
missense
reverse
nonsense
silent

nonsense

A mutant E. coli strain, grown under conditions that normally induce the lac operon, does not produce ß-galactosidase. What is a possible genotype of the cells?
lacI+ lacP+ lacO+ lacZ+ lacY- lacA+
lacI+ lacP- lacO+ lacZ+ lacY+ lacA+
lacl+ lacP+ lacO+ lacZ+ lacY+ lacA+
lacI+ lacP+ lacOc lacZ+ lacY+ lacA+

lacI+ lacP- lacO+ lacZ+ lacY+ lacA+

What is the function of allolactose in regulation of the lac operon?
inducer
repressor
promoter
activator
regulatory protein

inducer

E. coli bacteria are placed into a medium containing glucose and lactose. Which of the genes below do you expect to be turned on?
f-galactosidase
Lac I
Lac P
Permease
None of the above

f-galactosidase
Lac I
Lac P
Permease
>None of the above

In what part of the mRNA does degradation generally begin?
at the 3' end with the removal of the methyl cap
at the 3' end with the removal of the poly(A) tail
at the 5' end with the removal of the methyl cap
Removal from either end is equally likely.
at the 5' end with the removal of the poly(A) tail

at the 5' end with the removal of the methyl cap

The lac repressor binds to:
d-galactosidase, permease and transacetylase.
promoter and lactose.
RNA polymerase and DNA.
lactose and DNA.
RNA polymerase.

lactose and DNA

A class of mutations which results in multiple contiguous amino acid changes in proteins is likely to be the following
a) recombinant
b) transition
c) base analogue
d) frameshift
e) transversion

frameshift

What is the function of cAMP in regulation of the lac operon?
It inactivates a repressor protein.
It activates a repressor protein.
It inactivates an activator protein.
It activates an activator protein.

It activates an activator protein.

What is a mutation?
a) A change of amino acid
b) A change in allele frequency
c) A change in the phenotype
d) A change in the DNA sequence

d) A change in the DNA sequence

__________ mutations produce new traits and are usually dominant.
Gain-of-function
Lethal
Induced
Spontaneous
Forward

Gain-of-function

An example of a gene product encoded by a regulatory gene is
allolactose.
repressor protein.
operator.
beta-galactosidase enzyme.

repressor protein

Regulation of gene expression using siRNAs is found in
prokaryotes only.
eukaryotes only.
prokaryotes and eukaryotes.

eukaryotes only

Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are called
error prone and spontaneous.
base analogues and frameshift
sense and antisense.
transversions and transitions
euchromatic and heterochromatic.

transversions and transitions

A mutation in the gene for the yeast regulatory protein GAL4 causes yeast to grow poorly on galactose. What is the function of GAL4?
It is a transcription repressor that prevents expression of yeast galactose-digesting enzymes.
It is a transcription activator for the galactose-digesting enzyme gene.
It is a substrate that binds and activates a transcriptional activator.
It is an enzyme that metabolizes galactose.
It is a product that binds and activates a transcriptional repressor.

It is a transcription activator for the galactose-digesting enzyme gene.

An operon is controlled by a repressor. When the repressor binds to a small molecule, it binds to DNA near the operon. The operon is constitutively expressed if a mutation prevents the repressor from binding to the small molecule.
positive repressible
negative inducible
negative repressible
positive inducible

negative repressible

An operon is controlled by a repressor. When the repressor binds to a small molecule, it is released from binding to DNA near the operon. The operon is never expressed if a mutation prevents the repressor from binding to the small molecule.
positive repressible
positive inducible
negative inducible
negative repressible

positive inducible

Alternative splicing is known to be important in the regulation of
the production of heat-shock elements.
the metallothionein gene.
the mammalian SV40 virus.
the lac operon in E. coli.

the mammalian SV40 virus.

In the absence of glucose and in the presence of galactose, several genes are activated to enable yeast utilize galactose. The key regulator(s) of the yeast GAL system is/are the _______ protein(s).
Gal80
Gal4
Gal3
All of the above
None of the above

Gal80
Gal4
Gal3
>All of the above
None of the above

In the previous diagram, if there is a mutation in P and I, which of the following is true?

These are mutations that are, respectively, cis and trans acting on lac operon expression.
These will affect the expression of I only.
These will affect the expression of only Z, Y, and A.
These are mutations that are, respectively, trans and cis acting on lac operon expression.

These are mutations that are, respectively, cis and trans acting on lac operon expression.

Nutritional mutations can be defined as
a) those mutations which do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium.
b) those mutations which change the composition of the medium.
c) all strains which are not auxotrophic.
d) those mutations which change the composition of the medium.
e) those mutations caused by site-specific mutagenesis

a) those mutations which do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium

What modification neutralizes the charges on histones that promote ionic interaction with DNA?
polyadenylation
phosphorylation
acetylation
demethylation

acetylation

The _________ can be used to quickly screen chemicals for their ability to be mutagenic (and hence potentially carcinogenic).

Ames test

_____________ are complexes where, among other activities, a great deal of RNA degradation takes place.

P bodies

The general term for a protein that binds to an operator.

repressor

When siRNAs are present, the rate of mRNA degradation_____________ and the rate of protein production ___________.

increases, decreases

Mutations in the promoter region of the b-globin gene indicate that some areas are more sensitive than others. When mutations occur in consensus sequences (modular elements such as GC box, CAAT box, TATA box) transcription ________

decreases

The __________ is a type of _________ protein that binds to a region of DNA in the promoter of a gene called the _________ and prevents ______________ from taking place.

repressor, regulator, operator, transcription

Degradation of a eukaryotic mRNA is generally preceded by shortening of the _____________.

poly (A) tail

A highly-methylated region of a chromosome that has become largely deactivated and can be seen as dense-regions when viewed using electron microscopy.

heterochromatin

This process moves a nucleosome from the TATA box of a gene's promoter so that transcription can occur

chromatin remodeling

Match each number with the closest type of DNA:
a. moderately repetitive DNA
b. highly repetitive DNA
c. short interspersed elements
d. long interspersed elements
e. unique-sequence DNA

moderately repetitive DNA rRNA, tRNA
highly repetitive DNA telomeres
short interspersed elements
long interspersed elements
unique-sequence DNA gene-encoding sequence

Recent discoveries on causes of fragile-X syndrome, myotonic dystrophy, and Huntington disease indicate what type of genetic alteration?

change in trinucleotide repeats

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